In U.S. Pat. No. 5,344,121 of the present inventor there is disclosed a winch which is designed particularly for use in protecting a person entering an underground or unsafe area so that the person can be supported against falling and can be returned to a safe location in the event that the person becomes incapacitated.
Winches of this type are now mandated when a person enters an underground location such as a tank or pipe line to ensure that the person is not injured by falling while entering the location and to ensure that the person can be retrieved to the surface in the event that the person becomes incapacitated due to injury or noxious gases.
Winches of this type are carefully manufactured to particular tolerances and also are of the type which include a braking system so that the cable is held against further paying out once it is pulled. A manually operable handle cranks the winch drum in a direction to pay out the cable and in a direction to reel in the cable. In the paying out direction the handle is cranked to release the brake so as to allow the cable to be gradually paid out at a rate determined by the manual cranking of the drum rather than by the rate of pulling. The cable is therefore winched down into the underground location with the person generally as the person climbs down an entry ladder. In the event of falling, the brake holds the drum against further rotation in the paying out direction and allows the operator on the surface to crank the drum in the reeling in direction to pull the person back to the surface.
It is of course important in winches of this type that they be maintained in proper operating condition so that there is no breakdown in an emergency situation. It is generally therefore not satisfactory that the winch is merely be repaired when broken but that there be a proper service procedure and time table by which it is maintained in proper operating condition.
Up till now, such a servicing procedure has been based upon a time period so that it is proposed that the winch be returned for servicing after a predetermined period of time for example six months to ensure that servicing is of sufficient frequency to prevent breakdown.
However this simple statement has generally been found to be insufficient to ensure that servicing occurs on the mandated time period. Generally the winch it self does not carry any indication of the date for servicing so that it is quite possible that the winch remains in operation for a period long past the due date. Generally nothing on the winch itself confirms to the operator that it is beyond its due date for service and therefore the winch is continued to be used. In practice this system does not lead to a proper servicing of the equipment.
Secondly this system does not take into account different levels of usage. Some winches of this type are used heavily on a repeated basis and some are merely available for an emergency situation and therefore are used very infrequently. The specification of a predetermined time period for service does not take into account these different levels of usage.